Implement a new custom extensions API

[openssl.git] / ssl / statem / extensions.c

diff --git a/ssl/statem/extensions.c b/ssl/statem/extensions.c
index c2e0411240669704d38864e9b5a116976dbc14e8..49a7156a2cfc3458a6ff1e1334e351daa458504d 100644 (file)
--- a/ssl/statem/extensions.c
+++ b/ssl/statem/extensions.c
@@ -329,6 +329,23 @@ static const EXTENSION_DEFINITION ext_defs[] = {
     }
 };
 
     }
 };
 

+/* Check whether an extension's context matches the current context */
+static int validate_context(SSL *s, unsigned int extctx, unsigned int thisctx)
+{
+    /* Check we're allowed to use this extension in this context */
+    if ((thisctx & extctx) == 0)
+        return 0;
+
+    if (SSL_IS_DTLS(s)) {
+        if ((extctx & SSL_EXT_TLS_ONLY) != 0)
+            return 0;
+    } else if ((extctx & SSL_EXT_DTLS_ONLY) != 0) {
+        return 0;
+    }
+
+    return 1;
+}
+

 /*
  * Verify whether we are allowed to use the extension |type| in the current
  * |context|. Returns 1 to indicate the extension is allowed or unknown or 0 to
 /*
  * Verify whether we are allowed to use the extension |type| in the current
  * |context|. Returns 1 to indicate the extension is allowed or unknown or 0 to


@@ -345,38 +362,31 @@ static int verify_extension(SSL *s, unsigned int context, unsigned int type,
 
     for (i = 0, thisext = ext_defs; i < builtin_num; i++, thisext++) {
         if (type == thisext->type) {
 
     for (i = 0, thisext = ext_defs; i < builtin_num; i++, thisext++) {
         if (type == thisext->type) {

-            /* Check we're allowed to use this extension in this context */
-            if ((context & thisext->context) == 0)
+            if (!validate_context(s, thisext->context, context))

                 return 0;
 
                 return 0;
 

-            if (SSL_IS_DTLS(s)) {
-                if ((thisext->context & SSL_EXT_TLS_ONLY) != 0)
-                    return 0;
-            } else if ((thisext->context & SSL_EXT_DTLS_ONLY) != 0) {
-                    return 0;
-            }
-

             *found = &rawexlist[i];
             return 1;
         }
     }
 
             *found = &rawexlist[i];
             return 1;
         }
     }
 

-    if ((context & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) == 0) {
-        /*
-         * Custom extensions only apply to <=TLS1.2. This extension is unknown
-         * in this context - we allow it
-         */
-        *found = NULL;
-        return 1;
-    }
-

     /* Check the custom extensions */
     if (meths != NULL) {
     /* Check the custom extensions */
     if (meths != NULL) {

-        for (i = builtin_num; i < builtin_num + meths->meths_count; i++) {
-            if (meths->meths[i - builtin_num].ext_type == type) {
-                *found = &rawexlist[i];
-                return 1;
-            }
+        size_t offset = 0;
+        int server = -1;
+        custom_ext_method *meth = NULL;
+
+        if ((context & SSL_EXT_CLIENT_HELLO) != 0)
+            server = 1;
+        else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0)
+            server = 0;
+
+        meth = custom_ext_find(meths, server, type, &offset);
+        if (meth != NULL) {
+            if (!validate_context(s, meth->context, context))
+                return 0;
+            *found = &rawexlist[offset + builtin_num];
+            return 1;

         }
     }
 
         }
     }
 


@@ -390,8 +400,7 @@ static int verify_extension(SSL *s, unsigned int context, unsigned int type,
  * the extension is relevant for the current context |thisctx| or not. Returns
  * 1 if the extension is relevant for this context, and 0 otherwise
  */
  * the extension is relevant for the current context |thisctx| or not. Returns
  * 1 if the extension is relevant for this context, and 0 otherwise
  */

-static int extension_is_relevant(SSL *s, unsigned int extctx,
-                                 unsigned int thisctx)
+int extension_is_relevant(SSL *s, unsigned int extctx, unsigned int thisctx)

 {
     if ((SSL_IS_DTLS(s)
                 && (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)
 {
     if ((SSL_IS_DTLS(s)
                 && (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)


@@ -399,7 +408,8 @@ static int extension_is_relevant(SSL *s, unsigned int extctx,
                     && (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
             || (SSL_IS_TLS13(s)
                 && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)
                     && (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
             || (SSL_IS_TLS13(s)
                 && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)

-            || (!SSL_IS_TLS13(s) && (extctx & SSL_EXT_TLS1_3_ONLY) != 0))
+            || (!SSL_IS_TLS13(s) && (extctx & SSL_EXT_TLS1_3_ONLY) != 0)
+            || (s->hit && (extctx & SSL_EXT_IGNORE_ON_RESUMPTION) != 0))

         return 0;
 
     return 1;
         return 0;
 
     return 1;


@@ -427,7 +437,7 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
     PACKET extensions = *packet;
     size_t i = 0;
     size_t num_exts;
     PACKET extensions = *packet;
     size_t i = 0;
     size_t num_exts;

-    custom_ext_methods *exts = NULL;
+    custom_ext_methods *exts = &s->cert->custext;

     RAW_EXTENSION *raw_extensions = NULL;
     const EXTENSION_DEFINITION *thisexd;
 
     RAW_EXTENSION *raw_extensions = NULL;
     const EXTENSION_DEFINITION *thisexd;
 


@@ -437,12 +447,8 @@ int tls_collect_extensions(SSL *s, PACKET *packet, unsigned int context,
      * Initialise server side custom extensions. Client side is done during
      * construction of extensions for the ClientHello.
      */
      * Initialise server side custom extensions. Client side is done during
      * construction of extensions for the ClientHello.
      */

-    if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
-        exts = &s->cert->srv_ext;
-        custom_ext_init(&s->cert->srv_ext);
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        exts = &s->cert->cli_ext;
-    }
+    if ((context & SSL_EXT_CLIENT_HELLO) != 0)
+        custom_ext_init(&s->cert->custext);

 
     num_exts = OSSL_NELEM(ext_defs) + (exts != NULL ? exts->meths_count : 0);
     raw_extensions = OPENSSL_zalloc(num_exts * sizeof(*raw_extensions));
 
     num_exts = OSSL_NELEM(ext_defs) + (exts != NULL ? exts->meths_count : 0);
     raw_extensions = OPENSSL_zalloc(num_exts * sizeof(*raw_extensions));


@@ -560,21 +566,11 @@ int tls_parse_extension(SSL *s, TLSEXT_INDEX idx, int context,
          */
     }
 
          */
     }
 

-    /*
-     * This is a custom extension. We only allow this if it is a non
-     * resumed session on the server side.
-     *chain
-     * TODO(TLS1.3): We only allow old style <=TLS1.2 custom extensions.
-     * We're going to need a new mechanism for TLS1.3 to specify which
-     * messages to add the custom extensions to.
-     */
-    if ((!s->hit || !s->server)
-            && (context
-                & (SSL_EXT_CLIENT_HELLO | SSL_EXT_TLS1_2_SERVER_HELLO)) != 0
-            && custom_ext_parse(s, s->server, currext->type,
-                                PACKET_data(&currext->data),
-                                PACKET_remaining(&currext->data),
-                                al) <= 0)
+    /* Parse custom extensions */
+    if (custom_ext_parse(s, context, currext->type,
+                         PACKET_data(&currext->data),
+                         PACKET_remaining(&currext->data),
+                         x, chainidx, al) <= 0)

         return 0;
 
     return 1;
         return 0;
 
     return 1;


@@ -595,11 +591,7 @@ int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
     const EXTENSION_DEFINITION *thisexd;
 
     /* Calculate the number of extensions in the extensions list */
     const EXTENSION_DEFINITION *thisexd;
 
     /* Calculate the number of extensions in the extensions list */

-    if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
-        numexts += s->cert->srv_ext.meths_count;
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        numexts += s->cert->cli_ext.meths_count;
-    }
+    numexts += s->cert->custext.meths_count;

 
     /* Parse each extension in turn */
     for (i = 0; i < numexts; i++) {
 
     /* Parse each extension in turn */
     for (i = 0; i < numexts; i++) {


@@ -621,6 +613,30 @@ int tls_parse_all_extensions(SSL *s, int context, RAW_EXTENSION *exts, X509 *x,
     return 1;
 }
 
     return 1;
 }
 

+int should_add_extension(SSL *s, unsigned int extctx, unsigned int thisctx,
+                         int max_version)
+{
+    /* Skip if not relevant for our context */
+    if ((extctx & thisctx) == 0)
+        return 0;
+
+    /* Check if this extension is defined for our protocol. If not, skip */
+    if ((SSL_IS_DTLS(s) && (extctx & SSL_EXT_TLS_IMPLEMENTATION_ONLY) != 0)
+            || (s->version == SSL3_VERSION
+                    && (extctx & SSL_EXT_SSL3_ALLOWED) == 0)
+            || (SSL_IS_TLS13(s)
+                && (extctx & SSL_EXT_TLS1_2_AND_BELOW_ONLY) != 0)
+            || (!SSL_IS_TLS13(s)
+                && (extctx & SSL_EXT_TLS1_3_ONLY) != 0
+                && (thisctx & SSL_EXT_CLIENT_HELLO) == 0)
+            || ((extctx & SSL_EXT_TLS1_3_ONLY) != 0
+                && (thisctx & SSL_EXT_CLIENT_HELLO) != 0
+                && (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION)))
+        return 0;
+
+    return 1;
+}
+

 /*
  * Construct all the extensions relevant to the current |context| and write
  * them to |pkt|. If this is an extension for a Certificate in a Certificate
 /*
  * Construct all the extensions relevant to the current |context| and write
  * them to |pkt|. If this is an extension for a Certificate in a Certificate


@@ -634,7 +650,7 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                              X509 *x, size_t chainidx, int *al)
 {
     size_t i;
                              X509 *x, size_t chainidx, int *al)
 {
     size_t i;

-    int addcustom = 0, min_version, max_version = 0, reason, tmpal;
+    int min_version, max_version = 0, reason, tmpal;

     const EXTENSION_DEFINITION *thisexd;
 
     /*
     const EXTENSION_DEFINITION *thisexd;
 
     /*


@@ -667,21 +683,10 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
 
     /* Add custom extensions first */
     if ((context & SSL_EXT_CLIENT_HELLO) != 0) {
 
     /* Add custom extensions first */
     if ((context & SSL_EXT_CLIENT_HELLO) != 0) {

-        custom_ext_init(&s->cert->cli_ext);
-        addcustom = 1;
-    } else if ((context & SSL_EXT_TLS1_2_SERVER_HELLO) != 0) {
-        /*
-         * We already initialised the custom extensions during ClientHello
-         * parsing.
-         *
-         * TODO(TLS1.3): We're going to need a new custom extension mechanism
-         * for TLS1.3, so that custom extensions can specify which of the
-         * multiple message they wish to add themselves to.
-         */
-        addcustom = 1;
+        /* On the server side with initiase during ClientHello parsing */
+        custom_ext_init(&s->cert->custext);

     }
     }

-
-    if (addcustom && !custom_ext_add(s, s->server, pkt, &tmpal)) {
+    if (!custom_ext_add(s, context, pkt, x, chainidx, max_version, &tmpal)) {

         SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
         goto err;
     }
         SSLerr(SSL_F_TLS_CONSTRUCT_EXTENSIONS, ERR_R_INTERNAL_ERROR);
         goto err;
     }


@@ -691,28 +696,13 @@ int tls_construct_extensions(SSL *s, WPACKET *pkt, unsigned int context,
                          size_t chainidx, int *al);
 
         /* Skip if not relevant for our context */
                          size_t chainidx, int *al);
 
         /* Skip if not relevant for our context */

-        if ((thisexd->context & context) == 0)
+        if (!should_add_extension(s, thisexd->context, context, max_version))

             continue;
 
         construct = s->server ? thisexd->construct_stoc
                               : thisexd->construct_ctos;
 
             continue;
 
         construct = s->server ? thisexd->construct_stoc
                               : thisexd->construct_ctos;
 

-        /* Check if this extension is defined for our protocol. If not, skip */
-        if ((SSL_IS_DTLS(s)
-                    && (thisexd->context & SSL_EXT_TLS_IMPLEMENTATION_ONLY)
-                       != 0)
-                || (s->version == SSL3_VERSION
-                        && (thisexd->context & SSL_EXT_SSL3_ALLOWED) == 0)
-                || (SSL_IS_TLS13(s)
-                    && (thisexd->context & SSL_EXT_TLS1_2_AND_BELOW_ONLY)
-                       != 0)
-                || (!SSL_IS_TLS13(s)
-                    && (thisexd->context & SSL_EXT_TLS1_3_ONLY) != 0
-                    && (context & SSL_EXT_CLIENT_HELLO) == 0)
-                || ((thisexd->context & SSL_EXT_TLS1_3_ONLY) != 0
-                    && (context & SSL_EXT_CLIENT_HELLO) != 0
-                    && (SSL_IS_DTLS(s) || max_version < TLS1_3_VERSION))
-                || construct == NULL)
+        if (construct == NULL)

             continue;
 
         if (!construct(s, pkt, context, x, chainidx, &tmpal))
             continue;
 
         if (!construct(s, pkt, context, x, chainidx, &tmpal))